Electric vehicles and hybrid vehicles include an electric rotary machine as a drive source. In particular, in hybrid vehicles, there have been strong demands for reducing much the size of an electric rotary machine module to save space where to install it for the purpose of enabling the coexistence with an engine or ensuring the riding comfort. On the other hand, there are demands for electric rotary machines of higher output, and to this end, various countermeasures have been studied including the increase in the number of turns of a stator coil, the generation of high voltages by improving the insulation performance and the like.
In a coil end construction of an electric rotary machine as shown in FIGS. 9 and 10, a coil 113 is made up of U-shaped coil segments 100 which are each made up of a bundle of flat angular wires W in which plural flat angular wires 101 are aligned together side by side and which each have a pair of leg portions 102 and a connecting portion 103 in which an S-shaped portion 104 which is curved into an S-shape is provided at a middle portion thereof and which connects both the leg portions 102 together (for example, refer to JP-2012-165624-A).
The coil 113 is formed by inserting a pair of leg portions 102 of each of plural coil segments 100 into different slots 112 in a stator core 111, forming a spanning portion 114 which spans from a radially inner side of one slot 112 to a radially outer side of the other slot 112 by the S-shaped portion 104, and folding projecting portions of the leg portions 102 which project from the stator core 111 in a circumferential direction so that corresponding leg portions 102 are connected together. By doing so, plural S-shaped portions 104 which each make up the spanning portion 114 of the coil segment 100 are disposed so as to overlap each other in the circumferential direction on one surface 111a of the stator core 111.
The coil segment 100 is formed based on a procedure shown in FIGS. 11A to 11C. Firstly, as shown in FIG. 11A, a central portion of a bundle of flat angular wires W in which plural flat angular wires 101 are aligned together with their wider surfaces arranged to be opposite to each other is bent by a movable die 121 and a fixed die 122 to form an S-shaped portion 104. Following this, as shown in FIG. 11B, the central portion of the bundle of flat angular wires W is pressed substantially into a V-shape by a projecting die 123 and a recessed die 124 which each have sloping surfaces of a predetermined angle on both left- and right-hand sides thereof to form sloping portions 105 on both sides of the S-shaped portion 104. Thereafter, as shown in FIG. 11C, the bundle of flat angular wires W is disposed on a leg portion forming die 125, and a pair of L-shaped dies 126 are lowered to bend both end portions of the bundle of flat angular wires W to form a pair of leg portions 102.
In JP-2012-165624-A, the surfaces of the flat angular wires 101 which face each other in the slot 112 are also made to face each other at the end of the coil so that the size of the electric rotary machine is reduced without affecting badly the insulation coatings of the flat angular wires 101.
However, in JP-2012-165624-A, as shown in FIGS. 12A and 12B, when attempting to form a coil end in which a spanning height is reduced by placing sloping portions 105 of adjacent coil segments 100A to 100C as close to each other as possible or contacting them together, in reality, as shown in FIG. 13A, a corner portion 101a of one of flat angular wires 101 of the coil segment 100A comes to interfere with the coil segment 100B at a transition portion 106 between the sloping portions 105 of the coil segment 100A, causing a problem that the insulation performance is reduced. Because of this, when attempting to ensure an insulating distance required at the transition portion 106 or to form a coil end via an insulating material, as shown in FIG. 13B, the sloping portions 105 are spaced apart from each other or the spanning height is increased, which increases the size of the electric rotary machine, causing a problem that the installation of the electric rotary machine into a vehicle is deteriorated.